1. Field of the Invention
This invention relates to a method and circuit for speed control selection in an electronically commutated motor.
2. Description of the Prior Art
FIG. 1 shows the conventional method of speed control selection in an electronically commutated motor, i.e., the motor's running speed being controlled by a wire selection method. Each input wire connected to the motor controller can input a low voltage or high voltage signal (i.e. a digital 0 or 1 signal). Therefore when there are N wires, the maximum number of optional speeds is 2N.
However, this conventional method has the disadvantage: the speed selection wires are so excessive that the structure is very complex, difficult to integrate, and expensive. Accordingly, much opportunity exists for improvement in this area of technology.